Rewrite chapter seeds: multi-event support, drop is_primary, fix data

- seed_chapter now accepts events: array instead of flat rrule:/
  start_time: params; each event hash supports rrule:, start_time:,
  tag_list:, location:, duration_hours:
- Chapters with multiple open days now represented correctly
  (Stralsund: Thursday Chaostreff + 2nd/4th Saturday OpenSpace;
  Hamburg: 2nd Friday + last Tuesday; Stuttgart: 1st Tuesday +
  3rd Wednesday; Freiburg: Mon+Tue open + biweekly Plenum;
  Backnang: 3rd Sunday + 1st Tuesday; Tübingen: last Sunday +
  2nd Monday at different venues)
- is_primary removed from migration entirely — replaced by
  tag_list: 'open-day' on events
- Stale EN descriptions corrected: Berlin, Darmstadt, Erlangen,
  Essen, Freiburg, Göttingen, Hamburg, Hannover, Karlsruhe,
  Paderborn, Stuttgart, Ulm
- chaostreff-stralsund duplicate entry removed (Port39 is erfa only)

1 files changed, 0 insertions, 5 deletions

diff --git a/db/migrate/20260627233640_upgrade_events_and_nodes_for_standalone_events.rb b/db/migrate/20260627233640_upgrade_events_and_nodes_for_standalone_events.rb
index 790a62b..2605e5c 100644
--- a/db/migrate/20260627233640_upgrade_events_and_nodes_for_standalone_events.rb
+++ b/db/migrate/20260627233640_upgrade_events_and_nodes_for_standalone_events.rb
@@ -4,10 +4,6 @@ class UpgradeEventsAndNodesForStandaloneEvents < ActiveRecord::Migration[8.1]
     change_column_null :events, :node_id, true
     add_column :events, :title,       :string
     add_column :events, :description, :text
-    add_column :events, :is_primary,  :boolean, default: false, null: false
-
-    # Mark all existing events as primary (they were all 1:1 with nodes)
-    Event.where.not(node_id: nil).update_all(is_primary: true)
 
     # Occurrences: make node optional
     change_column_null :occurrences, :node_id, true
@@ -19,7 +15,6 @@ class UpgradeEventsAndNodesForStandaloneEvents < ActiveRecord::Migration[8.1]
   def down
     remove_column :nodes,       :external_url
     change_column_null :occurrences, :node_id, false
-    remove_column :events, :is_primary
     remove_column :events, :description
     remove_column :events, :title
     change_column_null :events, :node_id, false